The underframe for many railcars includes a center sill with a pair of end sills and a pair of side sills arranged in a rectangular configuration corresponding approximately with the dimensions for the floor of the freight car. Cross bearers and cross ties are often provided to establish the desired rigidity and strength for transmission of vertical loads to the center sill. A plurality of longitudinal stringers are typically provided on each side of the center sill to support the floor of the enclosed structure. Nailable metal floors are typically mounted to the underframe to provide a horizontal planar support surface for supporting the load to be carried in the freight car. The floor is nailable to provide for securing the load to prevent shifting during transport and is especially needed when the freight car is only partially loaded.
Nailable metal floors are typically comprised of several nested metal planks. This arrangement results in complex construction of the floor panels and a series of grooves in each floor panel. An example of a railway car nailable floor is disclosed in U.S. Pat. No. 4,224,880, which is incorporated herein by reference. Referring to the figure numbers of the patent, a U-shaped support member 6 is fixedly attached to the underside of the plank 2 in order to support the nailable floor from the underframe of the vehicle. What is needed is an improved design for a railcar nailable floor that reduces the cost of manufacture and reduces the weight of the floor thereby increasing the payload.